[MARMAM] New Publication: Lactation & resource limitation affect physiological responses of sea otters

Sarah Chinn sarahchinn at gmail.com
Tue Jul 31 19:54:46 PDT 2018

 Hello MARMAMers!

My co-authors and I are excited to share our new manuscript: "Lactation and
resource limitation affect stress responses, thyroid hormones, immune
function, and antioxidant capacity of sea otters" published in Ecology and

Chinn SM, Monson DH, Tinker MT, Staedler MM, Crocker DE. Lactation and
resource limitation affect stress responses, thyroid hormones, immune
function, and antioxidant capacity of sea otters (Enhydra lutris). Ecol
Evol. 2018;00:1–15. https://doi.org/10.1002/ece3.4280


Lactation is the most energetically demanding stage of reproduction in
female mammals. Increased energetic allocation toward current reproduction
may result in fitness costs, although the mechanisms underlying these
trade-offs are not well understood. Trade-offs during lactation may include
reduced energetic allocation to cellular maintenance, immune response, and
survival and may be influenced by resource limitation. As the smallest
marine mammal, sea otters (*Enhydra lutris*) have the highest mass-specific
metabolic rate necessitating substantial energetic requirements for
survival. To provide the increased energy needed for lactation, female sea
otters significantly increase foraging effort, especially during
late-lactation. Caloric insufficiency during lactation is reflected in the
high numbers of maternal deaths due to End-Lactation Syndrome in the
California subpopulation. We investigated the effects of lactation and
resource limitation on maternal stress responses, metabolic regulation,
immune function, and antioxidant capacity in two subspecies of wild sea
otters (northern: *E. l. nereis *and southern: *E. l. kenyoni*) within the
California, Washington, and Alaska subpopulations. Lactation and resource
limitation were associated with reduced glucocorticoid responses to acute
capture stress. Corticosterone release was lower in lactating otters.
Cortisol release was lower under resource limitation and suppression during
lactation was only evident under resource limitation. Lactation and
resource limitation were associated with alterations in thyroid hormones.
Immune responses and total antioxidant capacity were not reduced by
lactation or resource limitation. Southern sea otters exhibited higher
concentrations of antioxidants, immunoglobulins, and thyroid hormones than
northern sea otters. These data provide evidence for allocation trade-offs
during reproduction and in response to nutrient limitation but suggest
self-maintenance of immune function and antioxidant defenses despite
energetic constraints. Income-breeding strategists may be especially
vulnerable to the consequences of stress and modulation of thyroid function
when food resources are insufficient to support successful reproduction and
may come at a cost to survival, and thereby influence population trends.
Please use this link to access a copy of the article:

I am also happy to provide a .pdf copy, please email me:
sarahchinn at gmail.com

Thank you,
Sarah Chinn

PhD Candidate
Savannah River Ecology Laboratory
Warnell School of Forestry & Natural Resources
University of Georgia
Aiken, SC 29803
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